Modern gas turbine engines, particularly those utilized in aircraft applications, are using higher and higher air temperatures at the compressor outlet in order to increase the power and efficiency of the gas turbine engine. A certain quantity of hot and pressurized air is bled off at various stages of the compressors of gas turbine engines, referred to as compressor bleed air, to be used for various purposes. However, in some cases the hot compressor bleed air must be cooled before leading it to the user units such as air conditioning units providing air conditioning in a cabin of the aircraft. Therefore, a cooling system, and heat exchange in particular are required, which usually uses a portion of a bypass airflow bled off the bypass air duct of a turbofan gas turbine engine. Compact heat exchangers are usually required in this type of cooling system. Various compact heat exchangers of air/air type and various cooling systems in the prior art are available for aircraft engine applications. However, continuous efforts have been made to improve those heat exchangers and cooling systems in order to minimize the size and weight of the heat exchangers and cooling systems, while satisfying the required cooling capacity of the heat exchangers and cooling systems in aircraft engine applications.
Accordingly, there is a need to provide an improved cooling system for cooling compressor bleed air in turbofan gas turbine engines.